The invention relates to a transformer system having a transformer housing that receives a voltage converter and having an electrical terminal electrically connected to the voltage converter and extended out of the transformer housing for connecting the transformer system to a high- or medium-voltage system.
Such transformer systems are known. For constant monitoring of the high voltage, they are connected to high-voltage systems, such as switching stations, and typically mounted solidly. For maintenance or test purposes, however, the known transformer systems have to be detached. Particularly for a direct voltage cable test performed in the high-voltage system, an inductive voltage converter has to be removed; otherwise it would unavoidably be destroyed entirely when the test is performed.
In many high-voltage systems with sockets for the connection of high-voltage cables and voltage converters, the known transformer system also has to be detached for a different reason. Often there is no longer any unoccupied socket in the switching station to which a test cable for delivering the direct voltage can be connected. The voltage converter must then already be detached for that reason to allow the test cable to be connected to the socket previously occupied by the voltage converter.
To perform the voltage test, the following steps are necessary in the known systems:
The voltage converter is detached.
The socket that is now available is occupied by the test cable.
The direct voltage test is performed.
The test cable is detached.
The voltage converter is installed again.
Performing this procedure is time-consuming and expensive.
It is therefore the object of the present invention to disclose a transformer system of the type referred to at the outset with which a voltage test in a high-voltage system can be performed more simply.
This object is attained according to the invention in that a decoupling system actuatable from outside the transformer housing for temporarily interrupting the electrical connection between the voltage converter and the first terminal is disposed in the transformer housing.
The transformer system of the invention permits the electrical decoupling of the voltage converter from the high-voltage system without having to detach anything. The direct voltage test can then be performed without destroying the voltage converter.
In a further feature of the invention, it is provided that a further electrical terminal extended to the outside is provided, which is connected to the first electrical terminal via a connection capable of carrying current. A test cable for the direct voltage supply can, again without detachment of the transformer system, be connected to the further electrical terminal extended to the outside. The connection capable of carrying current according to the invention reliably carries the test voltages or currents on to the first electrical terminal connected to the high-voltage system.
If the first electrical terminal is embodied as a plug contact for being plugged into a socket of a high-voltage system, and the further electrical terminal is embodied as a socket, then the transformer system of the invention can be connected in an especially simple way to the high-voltage system and the test cable. With a view to compatibility, it is especially expedient here if the bush and the plug contact are embodied as an inside cone in accordance with German Industrial Standard DIN 47637 or as an outside cone in accordance with DIN 47636.
A first embodiment of the invention provides that the insulation is embodied of cast resin; that the decoupling system has two contacts embedded in the cast resin and one hollow chamber, into which a bridge element serving the purpose of electrical connection of the contacts can be inserted. Thus all the components can be embedded in the cast resin housing in a single operation, and the voltage-carrying parts are also electrically insulated in the same operation.
In a further feature of the invention, it is provided that the hollow chamber, accessible from outside through an introduction opening of the transformer housing, is embodied conically and the bridge element is embodied in rod form; that the contacts are disposed on the axial ends of the hollow chamber; and that the bridge element can be introduced into and retracted out of the conical hollow chamber axially through the introduction opening. Because of its rod form, the bridge element can be installed in a simple way by being plugged axially into the conical hollow chamber. In the process, it is guided by the conical form of the hollow chamber precisely to the rear contact, against which it has to be pressed.
If the introduction opening is embodied in the form of a bush, preferably in the form of a conventional high-voltage socket, in particular in accordance with the aforementioned DIN standard, and is closable by means of a cap, then for construction and manufacture a standardized shape that has already been used many times in other contexts and has stood the test of time can be employed, which reduces construction and production costs.
The provision of a dummy cable plug disposed in the introduction opening between the bridge element (20) and the cap assures the conditions for touch protection, because of the high-voltage strength of the dummy cable plug.
The provision that on being inserted, the bridge element can be pressed against the first contact, disposed opposite the introduction opening, via an axially acting spring element assures simple and reliable contacting as the bridge element is being plugged in.
If the second contact, disposed on the end of the hollow chamber toward the introduction opening, is embodied as a contact ring, with a through opening and axially acting contact element, then the bridge element can be introduced without problems through the contact ring into the conical hollow chamber. After that, a secure electrical contact is made by means of the axially acting contact elements.
In a refinement of the invention, the hollow chamber, in the decoupled state, can be provided not with the removed dummy cable plug and bridge element but instead with a special dummy plug of an elastic material, which fills up the hollow chamber and decouples the two contacts from one another in a high-voltage-proof fashion. By this provision the internal decoupling distance between the two contacts can be reduced to a minimum spacing because the elastic dummy plug presses flat against the inner surfaces of the hollow chamber and in particular against the contact faces as well and in the process positively displaces the air out of the ac. This prevents sparkovers that could otherwise occur between the contacts in the air-filled hollow chamber. Along with this provision, however, the total dimensions of the transformer housing, its weight, and the production costs are also reduced.
The invention can be improved still further by providing that the dummy plug is connected to a cap part that can be screwed instead of the cap to the transformer housing. The dummy plug with a cap plug guarantees the conditions for touch protection, because of its high-voltage strength.
Further advantages and details of the invention will become apparent from the ensuing description of exemplary embodiments in conjunction with the drawings.